/* * CBUS I2C driver for Nokia Internet Tablets. * * Copyright (C) 2004-2010 Nokia Corporation * * Based on code written by Juha Yrjölä, David Weinehall, Mikko Ylinen and * Felipe Balbi. Converted to I2C driver by Aaro Koskinen. * * This file is subject to the terms and conditions of the GNU General * Public License. See the file "COPYING" in the main directory of this * archive for more details. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #include #include #include #include #include #include #include #include #include #include /* * Bit counts are derived from Nokia implementation. These should be checked * if other CBUS implementations appear. */ #define CBUS_ADDR_BITS 3 #define CBUS_REG_BITS 5 struct cbus_host { spinlock_t lock; /* host lock */ struct device *dev; struct gpio_desc *clk; struct gpio_desc *dat; struct gpio_desc *sel; }; /** * cbus_send_bit - sends one bit over the bus * @host: the host we're using * @bit: one bit of information to send */ static void cbus_send_bit(struct cbus_host *host, unsigned bit) { gpiod_set_value(host->dat, bit ? 1 : 0); gpiod_set_value(host->clk, 1); gpiod_set_value(host->clk, 0); } /** * cbus_send_data - sends @len amount of data over the bus * @host: the host we're using * @data: the data to send * @len: size of the transfer */ static void cbus_send_data(struct cbus_host *host, unsigned data, unsigned len) { int i; for (i = len; i > 0; i--) cbus_send_bit(host, data & (1 << (i - 1))); } /** * cbus_receive_bit - receives one bit from the bus * @host: the host we're using */ static int cbus_receive_bit(struct cbus_host *host) { int ret; gpiod_set_value(host->clk, 1); ret = gpiod_get_value(host->dat); gpiod_set_value(host->clk, 0); return ret; } /** * cbus_receive_word - receives 16-bit word from the bus * @host: the host we're using */ static int cbus_receive_word(struct cbus_host *host) { int ret = 0; int i; for (i = 16; i > 0; i--) { int bit = cbus_receive_bit(host); if (bit < 0) return bit; if (bit) ret |= 1 << (i - 1); } return ret; } /** * cbus_transfer - transfers data over the bus * @host: the host we're using * @rw: read/write flag * @dev: device address * @reg: register address * @data: if @rw == I2C_SBUS_WRITE data to send otherwise 0 */ static int cbus_transfer(struct cbus_host *host, char rw, unsigned dev, unsigned reg, unsigned data) { unsigned long flags; int ret; /* We don't want interrupts disturbing our transfer */ spin_lock_irqsave(&host->lock, flags); /* Reset state and start of transfer, SEL stays down during transfer */ gpiod_set_value(host->sel, 0); /* Set the DAT pin to output */ gpiod_direction_output(host->dat, 1); /* Send the device address */ cbus_send_data(host, dev, CBUS_ADDR_BITS); /* Send the rw flag */ cbus_send_bit(host, rw == I2C_SMBUS_READ); /* Send the register address */ cbus_send_data(host, reg, CBUS_REG_BITS); if (rw == I2C_SMBUS_WRITE) { cbus_send_data(host, data, 16); ret = 0; } else { ret = gpiod_direction_input(host->dat); if (ret) { dev_dbg(host->dev, "failed setting direction\n"); goto out; } gpiod_set_value(host->clk, 1); ret = cbus_receive_word(host); if (ret < 0) { dev_dbg(host->dev, "failed receiving data\n"); goto out; } } /* Indicate end of transfer, SEL goes up until next transfer */ gpiod_set_value(host->sel, 1); gpiod_set_value(host->clk, 1); gpiod_set_value(host->clk, 0); out: spin_unlock_irqrestore(&host->lock, flags); return ret; } static int cbus_i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, char read_write, u8 command, int size, union i2c_smbus_data *data) { struct cbus_host *chost = i2c_get_adapdata(adapter); int ret; if (size != I2C_SMBUS_WORD_DATA) return -EINVAL; ret = cbus_transfer(chost, read_write == I2C_SMBUS_READ, addr, command, data->word); if (ret < 0) return ret; if (read_write == I2C_SMBUS_READ) data->word = ret; return 0; } static u32 cbus_i2c_func(struct i2c_adapter *adapter) { return I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA; } static const struct i2c_algorithm cbus_i2c_algo = { .smbus_xfer = cbus_i2c_smbus_xfer, .smbus_xfer_atomic = cbus_i2c_smbus_xfer, .functionality = cbus_i2c_func, }; static void cbus_i2c_remove(struct platform_device *pdev) { struct i2c_adapter *adapter = platform_get_drvdata(pdev); i2c_del_adapter(adapter); } static int cbus_i2c_probe(struct platform_device *pdev) { struct i2c_adapter *adapter; struct cbus_host *chost; adapter = devm_kzalloc(&pdev->dev, sizeof(struct i2c_adapter), GFP_KERNEL); if (!adapter) return -ENOMEM; chost = devm_kzalloc(&pdev->dev, sizeof(*chost), GFP_KERNEL); if (!chost) return -ENOMEM; if (gpiod_count(&pdev->dev, NULL) != 3) return -ENODEV; chost->clk = devm_gpiod_get_index(&pdev->dev, NULL, 0, GPIOD_OUT_LOW); if (IS_ERR(chost->clk)) return PTR_ERR(chost->clk); chost->dat = devm_gpiod_get_index(&pdev->dev, NULL, 1, GPIOD_IN); if (IS_ERR(chost->dat)) return PTR_ERR(chost->dat); chost->sel = devm_gpiod_get_index(&pdev->dev, NULL, 2, GPIOD_OUT_HIGH); if (IS_ERR(chost->sel)) return PTR_ERR(chost->sel); gpiod_set_consumer_name(chost->clk, "CBUS clk"); gpiod_set_consumer_name(chost->dat, "CBUS dat"); gpiod_set_consumer_name(chost->sel, "CBUS sel"); adapter->owner = THIS_MODULE; adapter->class = I2C_CLASS_HWMON; adapter->dev.parent = &pdev->dev; adapter->dev.of_node = pdev->dev.of_node; adapter->nr = pdev->id; adapter->timeout = HZ; adapter->algo = &cbus_i2c_algo; strscpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name)); spin_lock_init(&chost->lock); chost->dev = &pdev->dev; i2c_set_adapdata(adapter, chost); platform_set_drvdata(pdev, adapter); return i2c_add_numbered_adapter(adapter); } #if defined(CONFIG_OF) static const struct of_device_id i2c_cbus_dt_ids[] = { { .compatible = "i2c-cbus-gpio", }, { } }; MODULE_DEVICE_TABLE(of, i2c_cbus_dt_ids); #endif static struct platform_driver cbus_i2c_driver = { .probe = cbus_i2c_probe, .remove = cbus_i2c_remove, .driver = { .name = "i2c-cbus-gpio", .of_match_table = of_match_ptr(i2c_cbus_dt_ids), }, }; module_platform_driver(cbus_i2c_driver); MODULE_ALIAS("platform:i2c-cbus-gpio"); MODULE_DESCRIPTION("CBUS I2C driver"); MODULE_AUTHOR("Juha Yrjölä"); MODULE_AUTHOR("David Weinehall"); MODULE_AUTHOR("Mikko Ylinen"); MODULE_AUTHOR("Felipe Balbi"); MODULE_AUTHOR("Aaro Koskinen "); MODULE_LICENSE("GPL");